Which eggs to harvest?

Sorry if this sounds dumb..... We just bought our first ducks! We have had chickens for years but never had a rooster. We want them to hatch eggs but we also want to eat their eggs. How can you tell the new eggs from the fertile ones?

Well, what you want to do is just mark all a duck's eggs once she goes broody. Just draw an X on them. Then when you collect eggs, just take the ones without an X and momma duck will get to keep the ones she's incubating. This is what I do with my ducks and chickens and it works well.